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Author Topic: 68' Z/28 Hold off Valve  (Read 11096 times)

dannystarr

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68' Z/28 Hold off Valve
« on: January 18, 2009, 12:28:50 AM »
Hello fellow car buffs. New member here......Does anybody know what the average time span should be between the build date of the car, and the date of the rear holdoff valve. You know the proportioing valve mounted to the left frame rail under the car. It'a about where the driver would sit. It looks to be brass or bronze and has a brake line going in, and back out to the rear brakes. It has some letters and numbers on it. The car is a 4th week of Jan. 68' build, and if it matters the Engine assembly date is Jan. 3rd 68'. I have heard no more then 30 days, and another person at a swap meet said 65 days?? By the way it is a LOS built car. Thanx for your time eh..... D
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Camaro Billy

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Re: 68' Z/28 Hold off Valve
« Reply #1 on: January 18, 2009, 03:47:33 PM »
Mine is original on my 1969 SS. It has a Julian date code of 275-8 (Oct. 1st. 1968)
My car is a Norwood 11D build (4th week of Oct. 1968)
So mine is dated about 3 weeks before the car was built.
Billy
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dannystarr

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Re: 68' Z/28 Hold off Valve
« Reply #2 on: January 18, 2009, 04:21:51 PM »
Thanx Billy, that's a good start. Hopefully more Z/28 owners chime in... especially early to mid year 68' owners. Has to be somone out there that has a later in Jan. 68' build date. Would be nice to get an LOS built car close in date.......Danny
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JohnZ

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Re: 68' Z/28 Hold off Valve
« Reply #3 on: January 18, 2009, 05:15:48 PM »
That's not the hold-off valve, it's the rear proportioning valve - the hold-off valve is the round one in the front brake pipe below the master cylinder.

The proportioning valve on my Norwood 02D '69 Z/28 (built February 27th) is dated January 16th.
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Marty

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Re: 68' Z/28 Hold off Valve
« Reply #4 on: January 18, 2009, 05:40:27 PM »
My car was built in LOS the third week of January 68 and the rear proportioning valve is dated 3447.

Martin
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Martin Foltz
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68 Van Nuys Camaro

1968RSZ28

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Re: 68' Z/28 Hold off Valve
« Reply #5 on: January 18, 2009, 06:03:02 PM »
Quote from: dannystarr on January 18, 2009, 04:21:51 PM
Hopefully more Z/28 owners chime in... especially early to mid year 68' owners. Has to be somone out there that has a later in Jan. 68' build date. Would be nice to get an LOS built car close in date.......Danny

Danny -

My 02C LOS built 1968 Z/28 does not have a rear brake line pressure regulator valve.

Paul
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fireZ

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Re: 68' Z/28 Hold off Valve
« Reply #6 on: January 18, 2009, 06:37:51 PM »
I will check my 1968  02E Los built Z when I am off work today. I know it is on the car but cannot remember the date.
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Bucky L78

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Re: 68' Z/28 Hold off Valve
« Reply #7 on: January 18, 2009, 10:02:07 PM »
Danny
  My 02C Canadian sold and documented 68 Z does not have the rear proportioning valve on the subframe .I have read that not all 68 Z's had this valve,if I remember right it was changed throughout the year.
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Bucky L78

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Re: 68' Z/28 Hold off Valve
« Reply #8 on: January 18, 2009, 10:05:38 PM »
I should of added my 02C Z is a Norwood built car
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68Zproject

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Re: 68' Z/28 Hold off Valve
« Reply #9 on: January 18, 2009, 11:32:01 PM »
None on mine  either.  05D build date
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fireZ

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Re: 68' Z/28 Hold off Valve
« Reply #10 on: January 19, 2009, 12:43:50 AM »
Just dug through the snow to get into my garage and the hold off valve on my 02E Los built Z28 is  038  8 .
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fireZ

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Re: 68' Z/28 Hold off Valve
« Reply #11 on: January 19, 2009, 12:48:12 AM »
Sorry i meant to say  rear proportioning valve
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dannystarr

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Re: 68' Z/28 Hold off Valve
« Reply #12 on: January 19, 2009, 07:01:03 AM »
Well guys thank you all VERY much for the info so far. Seems they really can be dated anywhere from 20 days to 6 weeks! Thanx for all the effort. Digging thru the snow and the like. I have seen some cars with out the valves my self. And I have heard them called 6 different things. BUT, I will not cause a stir about this, and I will quite calling it a hold-off valve. Funny cause it DOES hold off SOME fluid to the rear brakes. Heck it is even metering the amount that travels back there. All the while letting just a certain proportion thru. OK, had to do that sorry.......Worked 12 hours straight today with no lunch. Just two bottled waters. Gotta call it a night.........Danny 
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